It is a common agricultural practice to spray products in aerosol form, such as pesticides, over agricultural fields to improve culture of crops of various types. One major problem with this practice is the lack of control over, and knowledge of, the final destination of the sprayed aerosol. The cloud of sprayed particles are easily carried away from the immediate vicinity of the sprayer by winds, and may land in is locations where they are damageable to the environment or the population, such as nearby streams, fields, residential areas, etc. Traditionally, qualified personnel rely on weather information, in particular wind direction and velocity, in order to estimate where the sprayed particles will go, but this technique lacks precision and there is no way to quickly verify if the operator's assumptions are correct.
One partial solution to this problem using optical technology has been proposed in U.S. Pat. No. 6,862,083 (McCONNELL Sr. et al). McCONNELL suggests the use of a rangefinder, an optical sensor using a pulsed laser beam to measure the distance of solid objects. The rangefinder can detect the presence of trees and classify them according to height, width and tree foliage volume. This information is used to map an orchard or grove and determine what amount of chemical products such as pesticides or the like should be applied to each tree. This system is not however appropriate for crops where solid objects cannot be found. In addition, it does not take into consideration the drift of the aerosol particles when applied.
Research in recent years has demonstrated that control of sprayed pesticides requires the direct measurement of the progression of the sprayed aerosol particles, not a measurement of surrounding vegetation. It is known, in the context of such research, to use traditional long-range LIDAR systems for measuring the drift of pesticides over a field. For example, in the publication by Miller D. R. et al entitled “Remote measurement of spray drift from orchard sprayers using LIDAR”(ASAE paper n. 031093 St-Joseph Mich. 2003), there is shown such a use where the long-range, expensive LIDAR sensor is positioned at one corner of a field and scanned over this field as the pesticide is sprayed. Although this document and other similar research provide valuable information on the parameters influencing the drift of pesticides and their effect on the environment, they do not provide a solution to the control of day-to-day spraying operations.
There is therefore a need for a system allowing the real-time measurement and control of the drift of aerosol particles sprayed over a field.